What should you test your well water for?
Most health agencies recommend testing a private well at least once a year for total coliform bacteria, and periodically for nitrates and other contaminants common in your area. Local geology and nearby land use decide the extras: arsenic, manganese, lead, radon, PFAS, or contaminants from farming or drilling.
How to do it
- Every year: total coliform bacteria (and E. coli if coliform is present).
- Every few years: nitrates, pH, hardness, iron and manganese.
- Ask your county health department or extension office which local contaminants to add.
- Retest after flooding, well repairs, or any change in taste, color or smell.
- Use a state-certified lab and follow its sampling instructions exactly.
What to avoid
- Don't collect bacteria samples from a hose, outside tap or a faucet with an aerator still on.
- Don't use a test kit past its hold time. Bacteria samples usually must reach the lab within about a day.
Certified labs
Wisconsin 25Ohio 21Minnesota 15Massachusetts 9Baltimore, MD 6Milwaukee, WI 6New Haven County, CT 5Maryland 5Hennepin County, MN 5Green Bay, WI 5Pennsylvania 4Fairfield County, CT 4Washington County, WI 4Walworth County, WI 4Connecticut 3Hartford County, CT 3Essex County, MA 3Summit County, OH 3Cincinnati, OH 3Franklin County, OH 3Stevens Point, WI 3Door County, WI 3Waukesha County, WI 3Racine County, WI 3Milwaukee County, WI 3Superior, WI 3Ozaukee County, WI 3Oshkosh, WI 3Port Washington, WI 3Madison, WI 3Stratford, CT 2Aberdeen, MD 2Harford County, MD 2Carroll County, MD 2Prince George's County, MD 2Anne Arundel County, MD 2Towson, MD 2Frederick County, MD 2Stevensville, MD 2Frederick, MD 2
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